1. Field of the Invention
This invention relates to wireless communications; and more particularly to an antenna for installation within a wireless communications device, and a manufacturing method of the same.
2. Description of the Related Art
In recent years, the field of wireless communications, including information technology (IT), has improved with the advent of the full-fledged information age, and there have been introduced various mobile devices such as cellular phones, digital cellular system (DCS), personal communication service (PCS), wideband code division multiple access (WCDMA), 4G long term evolution (LTE) phone, personal digital assistant (PDA) terminals, global positioning systems (GPS), smart phones, and notebook computers, among others, to provide a variety of services to users through wireless data communication.
An antenna such as helical antenna or dipole antenna is typically mounted on these mobile devices so as to enhance transmission intensity and receive sensitivity. These antennas, as an external antenna, are protruded to the outside of wireless communication terminals.
While the external antenna has useful radiation characteristics, being external to the mobile device presents problems such as breakage during normal use, de-tuning of the antenna due to direct contact with the user, and a negative impact on appearance and aesthetics.
As solutions to the abovementioned drawbacks, a flat internal antenna, such as a micro strip patch antenna or inverted F-type antenna, has been mounted within the terminal without protrusion to the outside thereof.
In general, the conventional internal antenna comprises a body molded with an insulator such as polycarbonate and a conductive pattern formed using a metal plate or etched conductive pattern on a flex circuit, for example, wherein the conductive pattern includes a circuit pattern capable of wireless transmission and reception in a specific frequency band and is coupled with the surface of the body.
To manufacture the internal antenna, there have been provided metal stamping method for punching a desired pattern into a metal piece and fusing the metal piece onto the molded body by heat, an etching method for plating the entire mold and eliminating the rest of mold except for the pattern; and a printing direct structuring (PDS) method for plating after directly printing the molded body with conductive ink.
The internal antenna is designed to transmit and receive the signal of a predetermined frequency band. In other words, the antenna may radiate the signal by resonance at a fixed frequency band.
In general, electrical characteristics of an antenna, such as radiation pattern, gain, bandwidth, frequency, polarization, and impedance, can be configured by varying the antenna design. For example, impedance of the antenna can be configured by providing a matching component such as a capacitor or an inductor. In conventional antennas, since matching components and antenna characteristic values are fixed, there is a problem that the new tuning of an internal antenna is required when the characteristic of antenna needs to be changed in the design process.
In other words, to obtain desired electric characteristics of the antenna, the conventional internal antenna requires a change in the design structure of the antenna through tuning according to the conditions of various systems, or to change the conditions of the system according to the characteristics of antenna. These limitations introduce added costs in the development process as well as difficulties in management of the product due to the development of various products.
To solve these problems, commonly owned Korean Patent Registration No. 10-0756312, entitled “RESONANCE FREQUENCY AND INPUT IMPEDANCE CONTROLLABLE MULTIPLEX BUILT-IN ANTENNA” discloses a built-in internal antenna, wherein the built-in antenna has one feeding point, two shorting points, and an inductor therebetween so as to control resonance frequency and input impedance.
In the above patent, however, there is a difficulty in process to install the inductor between the shorting point and the ground plane and it is difficult to install the built-in antenna with a PCB. Moreover, since only the inductor value is controlled from the outside of the built-in antenna, other electric characteristics of the built-in antenna are fixed.